Motion control of bicycle-riding exoskeleton robot with interactive force analysis

Exoskeleton robots are used to augment human power to perform difficult tasks. These robots can generate eternal load on human muscles as training devices. In this paper, a lower-limb training device using exoskeleton is developed for muscle power augmentation during cyclic motion. A control system determines augmenting power on the human leg during pedaling motion based on the calculation of muscle activity timing. The resulting power of the exoskeleton assists cycling motion as a rehabilitation system or applies mechanical load on the leg muscles as a training system. Measurement of interaction force by the load cell on each pedal determines admittance control signal. Experiments to assist bicycle riding motion using the developed exoskeleton were conducted. From the interaction force analysis, the sources of errors in the motion control are found, and the application-specific problems are discussed. Given that the exoskeleton robot can control hip and knee joint independently, the proposed system can be extended for assisting various motions in daily life, including walking rehabilitation.